Numerical investigation of forward, lateral, and backward injection of the coolant fluid in various flow characteristics to find the optimum film cooling effectiveness

Abstract

Film cooling is a major thermal protection method to protect the hot components in aero-engines like modern gas turbine blades. In this article, to find the optimum film cooling effectiveness, a numerical study was conducted in various forward, lateral, and backward injection angles (cross-flow injection angle $\mathrm{\phi }=0°,\mathrm{ }45°,\mathrm{ }90°,135°,180°)$ and flow characteristics. For validation, the predicted results are compared with available experimental data and are shown to be in good agreement. It is found that by increasing the density ratio (DR), the film cooling effectiveness of the holes with $\mathrm{\phi }=0°$ and $\mathrm{\phi }=90°$ increases, while the film cooling effectiveness with $\mathrm{\phi }=45°,\mathrm{ }135°,\text{ and }180°$ have a slight reduction. In addition, by increasing the injection angle from $\mathrm{\phi }=0°$ to $\mathrm{\phi }=180°,$ the film cooling effectiveness increases and has a maximum of $\mathrm{\phi }=90°.$ One of the most important results is optimum effectiveness, with $\mathrm{\phi }=90°$ (lateral injection) and velocity ratio (VR) = 0.5, DR = 1.79, and Tu = 2%.

Keywords:

• Film cooling effectiveness
• injection angle
• optimum effectiveness
• density ratio
• turbulence intensity
• velocity ratio